An object of the invention is to provide an exhaust emission control device which eliminates the use of a heat-retention structure using heat-insulating material such as glass wool so as to attain substantial lessening in production cost. A discharge end of a gas gathering chamber is connected to an entry end of a mixing pipe so as to encase the entry end of the mixing pipe and close an opened end face in a required spaced-apart relationship. Moreover, a side surface of the entry end of the mixing pipe adjacent to the discharge side of the particulate filter is formed with an opening; and gas guide passages are formed in the gas gathering chamber by guide fins for tangential introduction of all of the exhaust gas from the discharge side of the particulate filter to the opening. An extra space isolated from the gas guide passages is ensured in the gas gathering chamber as a heat-retention chamber surrounding the entry end of the mixing pipe.